WASTEWATER TREATMENT BY SPPO BASED THIN FILM COMPOSITE MEMBRANES

摘要

The pulp and paper industry is currently faced with the challenge of substantially reducing the discharge of contaminants to the receiving environment. Continuous progress has been made by the pulp and paper industry in reducing the fresh water use because of growing environmental concern. Water use reduction in a paper mill has been accomplished primarily by closing up the water system. This has however resulted in an increased concentration of suspended, dissolved and colloidal materials in the system, which in turn could result in a poor quality of paper and operational problems. Paper mills are therefore looking for alternative processes for internal treatment of water. Among the alternative processes, membrane separation process is getting an ever-increasing acceptance. One of the major problems of membrane application to pulp and paper stream treatment is the flux decline due to fouling. This problem has been addressed by developing thin film composite (TFC) membranes by coating a thin layer of sulfonated polyphenylene oxide (SPPO) on the surface of a porous substrate membrane. The membranes were tested for the treatment of solutions containing clay and styrene butadiene rubber (SBR) to stimulate the treatment of white water and coating effluent from the pulp and paper mill. Pure water permeation flux decreased on coating the substrate membrane with SPPO. However, the fouling was substantially reduced when the simulated wastewater was treated, due to the reduction in the cake layer resistance. It is believed that the repulsive force working between the negatively charged clay particles and the sulfonate groups on the membrane surface contributed to the fouling reduction.